In an office setting, coffee generally comes in little "sacks" of grounds that are proportioned to fill one pot. When one person puts in one package of coffee, he is said to have flopped a sack. Therefore, making coffee at work is to "flop a sack."
I went to the kitchen area and there was no more coffee left in the pot; therefore, I decided to flop a sack.
by officerat July 13, 2009

Auto erotic genital manipulation performed without the aid of one's hands. The flaccid penis is thrust about with aggressive hip movements and shuffling for between one and two hours or until erection occurs. The flopping off continues for another three to twelve hours when climax is finally achieved. Women with large clitori or labia minora may also engage in flopping off.
Guy 1: Man, I was flopping off like crazy yesterday. Took me like 13 hours but it was sweet, yo!
Guy 2: An all day floppoffathon? Gross!
Guy 2: An all day floppoffathon? Gross!
by Fatty Blumpkin March 17, 2015

by FlipperMan November 18, 2016

by yikeswhatshappening March 6, 2016

by TheRealRednecksofSEMO November 8, 2020

last night my cum hit me in the eye, must've been a cumflop.
simon: oi mark what happened to your eye.
mark: nothing just the wife sucked me off then my dick hit my belly button
simon: ah mark, that my friend is a cum flop.
simon: oi mark what happened to your eye.
mark: nothing just the wife sucked me off then my dick hit my belly button
simon: ah mark, that my friend is a cum flop.
by cumflop_salami_sandwich August 30, 2018

A non-erect or flaccid penis.
by 10010011 December 12, 2018
